# P value and 95% confidence Interval

I know that if a P value is less than 0.05 we can reject the null hypothesis and state that the finding may be statistically significant however I remember reading something about if the 95% confidence interval includes 0 that its not a significant finding or something like that (i tried to find what i was reading but couldnt find it again).

Im just wonder, if we have a p value below 0.05 but have a confidence interval including 0, how do we interpret this? Do we say that it is statistically significant but likely being caused by other factors?

Im just wonder, if we have a p value below 0.05 but have a confidence interval including 0, how do we interpret this?

It means that you took a confidence interval with more than 95% confidence. This is technically possible, but misleading to take the confidence interval at another $\alpha$ level than your test.

Existing software packages will give you p-values and CIs for the same $\alpha$ unless you force them to do something else.

• Thanks for the help, I've been sitting here for ages trying to work this out and just realized it was 0.1 not 0.01 for my p value ugh.
– Mick
Commented Dec 23, 2017 at 12:53